1. Field of the Invention
The present invention relates to an information recording method, an information recording medium and an information recording apparatus, using a recording medium in which information can be recorded by energy beam irradiation. Particularly, it relates to an information recording method having an excellent effect on a phase-change optical disk, an information recording medium, and an information recording apparatus using the information recording method.
2. Description of the Related Art
In the case of using, for example, such a photomagnetic disk as described in JP-A-62-175948 having a switched connection two-layer film as a recording film, or in the case of using, for example, such a high-speed erasable recording film for a phase-change optical disk as described in JP-A-62-259229 capable of performing crystallization in almost the same time as laser irradiation time for recording, a conventional recording/erasing method on a rewritable recording film is carried out by changing a power level of an energy beam between at least two power levels (that is, at least a high power level and an intermediate power level) which are higher than a read power level. The conventional method has an advantage in that new information can be recorded while existing information is erased, that is, overwriting (rewriting owing to overwriting) can be made. Further, such a phenomenon that a recording mark is shaped like a teardrop (a rear portion of a recording mark becomes wider than a front portion of the recording mark) can be suppressed by changing a power level of an energy beam among three power levels consisting of a high power level, an intermediate power level and a low power level lower than the intermediate power level as described in JP-A-62-259229 and JP-A-3-185629.
On the other hand, recently, a DVD-RAM using a phase-change material to achieve a memory capacity of 2.6 GB per side in a 120 mm-diameter disk has been put into practical use. A recording control method used in the DVD-RAM is described in JIS Standard, JIS X 6243 for 120 mm DVDRwritable Disk (DVD-RAM) (hereinafter referred to as xe2x80x9cStandard Book JIS X 6243xe2x80x9d), page 86. Control based on the aforementioned three power levels is described in the standard book.
Researches into improvement of the density of a rewritable digital video disk (DVD-RAM) using a phase-change recording film are in progress. In an optical disk device such as a DVD-RAM in which mark edge recording is performed in a phase-change recording film, both attained temperature and cooling speed in a recording mode need to be made substantially uniform in every place of an outer edge portion of a recording-film fused region for forming recording marks in the recording film in order to prevent both mark shape distortion and incomplete erasure. However, in various types of known recording waveforms, it is impossible to satisfy the condition sufficiently. Accordingly, there is a limitation in realizable recording density. Further, recording characteristic of a recording medium usually varies according to the producer, production time and lot of the recording medium. Accordingly, there is a tendency for recording compatibility to be more hardly secured as higher-density recording is intended.
Particularly, in a DVD-RAM with a memory capacity of 4.7 GB higher in density than the DVD-RAM with a memory capacity of 2.6 GB, recording is performed with the same spot diameter as that in the 2.6 GB DVD-RAM so that the compatibility with 2.6 GB DVD-RAM can be kept easily. However, when linear density is increased while the spot diameter is kept constant, the distance between positions irradiated on a recording medium by two recording pulses adjacent to each other is reduced compared with the light spot diameter of laser light on the recording medium. Accordingly, light distributions overlap each other compared with the 2.6 GB DVD-RAM, so that it is necessary to prevent the recording mark shape from being distorted due to the overlapping of light distributions. Therefore, it is thought of that more complicated modulated recording waveform control is used to increase the number of power levels so as to change the energy beam among four power levels. In such a complicated recording waveform, good-shape recording marks can be formed if appropriate setting is performed. Increase of the number of energy levels, however, brings about a problem of how to optimize the respective energy levels. That is, when the respective energy levels are set appropriately, good recording marks having little recording mark shape distortion can be formed. But, there is a problem that the procedure of optimizing the energy levels is complicated because energy balance becomes delicate and the number of energy levels is large (first problem).
In the conventional recording/erasing method applied to the rewritable recording film as described in the aforementioned Standard Book JIS X 6243, page 86, the control on the basis of the aforementioned three power levels is described. The recording power levels used in the recording mode are written in a control data area on the disk. The information recording apparatus sets the recording power levels by reading the recording power levels written on the disk. The absolute values of the recording power levels, however, may change due to the individual difference of the information recording apparatus, or due to the environmental change or aging of the information recording apparatus. In most cases, therefore, the recording power levels are checked or adjusted before information is written in the disk actually. That is, while Peak Power is changed in a condition that Bias Power 1 and Bias Power 2 given to the control data area are fixed, a random pattern is recorded and then reproduced to measure reproductive jitter. The recording power level to make the value of reproductive jitter equal to a predetermined value is multiplied by a predetermined factor so that a recording power level is obtained. The recording power level obtained thus is set as new Peak Power. Then, while Bias Power 1 is changed, the random pattern is recorded and then reproduced to measure the reproductive jitter. The bias power to minimize the value of the reproductive jitter is set as new Bias Power 1.
In a phase-change recording medium of a 120 mm diameter with a larger capacity than 2.6 GB per side (for example, a DVD-RAM with a diameter of 120 mm intended to achieve a capacity of 4.7 GB per side), accurate information recording may be performed by adaptively changing the timing of leading and trailing edge portions of a recording pulse in accordance with the combination of recording patterns to be recorded. It is thought of that such timing information is recorded in the control data area on the disk so that the information recording apparatus reads the timing information to use it for actual recording.
The information recording apparatus does not always have the same recording characteristic. The recording characteristic may change due to the individual difference of the information recording apparatus, or due to the aging or environmental change of the information recording apparatus. Accordingly, it may be impossible to perform appropriate recording on the basis of the timing information written on the disk. In such a case, the reproductive jitter at the time of recording/reproducing the random pattern becomes worse than the expected value. As a result, if the recording power levels are determined on the basis of the jitter of the random pattern in the same manner as that in the prior art, there is a possibility that the recording power levels may be set to unsuitable values. If the recording is performed on the basis of the unsuitable recording power levels, there is a fear of reduction in reliability of recording/reproducing, for example, the recording becomes unstable, the already written information is erased due to cross-erasure, and so on (second problem).
Further, as described above, in the DVD-RAM with the recording capacity of 4.7 GB which is higher in density than the 2.6 GB DVD-RAM, the recording can be performed with the same spot diameter as that in the 2.6 GB DVD-RAM so that the compatibility with the 2.6 GB DVD-RAM can be obtained. However, when the linear density is made high while the spot diameter is kept unchanged, the distance between two positions on the recording medium irradiated with two adjacent recording pulses is reduced compared with the light spot diameter of laser light on the recording medium. For this reason, the light distributions overlap each other compared with the case of 2.6 GB, so that it is necessary to prevent the recording mark shape distortion due to the overlapping of the light distributions.
Further, when the space between the recording marks is short, the recording marks cannot be resolved by the reading light spot, so that the shifting of the recording mark edge position occurs in the reproductive signal waveform. Accordingly, it is also necessary to prevent the recording mark edge position from shifting. For this reason, an attempt has been made to reduce the shifting of the recording mark edge position by changing the irradiation timing of the recording pulses according to the length of a mark to be written and the length of a portion (hereinafter referred to as xe2x80x9cspacexe2x80x9d) between marks. However, when high-density recording is to be performed by use of the phase-change medium such as a DVD-RAM with the recording capacity of 4.7 GB, there is a problem that the procedure for determining the irradiation timing of the recording pulses in detail is not always clear (third problem).
A first object of the present invention is to solve the aforementioned first problem, that is, to provide an information recording method and an information recording apparatus in which the accurate recording can be performed to improve density more greatly by use of the same spot diameter as that in the prior art while the compatibility with the prior art is kept. Particularly, the first object of the present invention is to provide an information recording method in which four energy levels for use in forming recording marks are selected easily and accurately, and to provide an information recording apparatus using the information recording method.
A second object of the present invention is to solve the aforementioned second problem, that is, to provide an information recording method and an information recording apparatus in which such unsuitable recording power levels as mentioned above are prevented from being set so that the stable recording/reproducing can be normally performed.
A third object of the present invention is to solve the aforementioned third problem, that is, to provide an information recording method, an information recording medium and an information recording apparatus in which the accurate recording can be performed to improve the density more greatly by use of the same spot diameter as that in the prior art while the compatibility with the prior art is kept. Particularly, the third object of the present invention is to provide a procedure for accurate measuring the irradiation timing of the recording pulse and a procedure for determining the optimum irradiation timing, an information recording apparatus using the measuring and determining procedures of the irradiation timing, and an information recording medium in which the irradiation timing determined using the measuring and determining procedures of the irradiation timing are recorded as fixed information.
To solve the aforementioned first problem, the following information recording method and apparatus may be used.
(1) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam and the first and second states are formed on the recording medium with predetermined lengths and at predetermined intervals, comprising the steps of:
providing a third power level equal to or less than the first power level;
making a period of the third power level coexistent with a period of the second power level to multi-pulsate the energy beam and irradiating the recording medium with the multi-pulsated energy beam when a region of the second state is formed in the recording medium so that the region of the second state has a specific length;
providing a fourth power level equal to or less than the first power level;
irradiating the recording medium with the fourth power level of the energy beam for a predetermined period following the last pulse of the multi-pulsated energy beam;
multiplying the second power level by a magnification factor x to thereby obtain a new second power level;
multiplying the first power level by a magnification factor y to thereby obtain a new first power level;
multiplying the third power level by the magnification factor y to thereby obtain a new third power level;
multiplying the fourth power level by the magnification factor y to thereby obtain a new fourth power level;
recording information on the recording medium while changing values of the magnification factors x and y variously, and reproducing the recorded information to thereby obtain a reproductive signal; and
adjusting the values of the magnification factors x and y so that a value of reproductive jitter of the reproductive signal is less than a predetermined value.
(2) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam and the first and second states are formed on the recording medium with predetermined lengths and at predetermined intervals, comprising the steps of:
providing a third power level equal to or less than the first power level;
making a period of the third power level coexistent with a period of the second power level to multi-pulsate the energy beam and irradiating the recording medium with the multi-pulsated energy beam when a region of the second state is formed in the recording medium so that the region of the second state has a specific length;
providing a fourth power level equal to or less than the first power level;
irradiating the recording medium with the fourth power level of the energy beam for a predetermined period following the last pulse of the multi-pulsated energy beam;
multiplying the first power level by a magnification factor z to thereby obtain a new first power level;
multiplying the second power level by the magnification factor z to thereby obtain a new second power level;
multiplying the third power level by the magnification factor z to thereby obtain a new third power level;
multiplying the fourth power level by the magnification factor z to thereby obtain a new fourth power level;
recording information on the recording medium while changing values of the magnification factor z variously, and reproducing the recorded information to thereby obtain a reproductive signal; and
adjusting the value of the magnification factor z so that a value of reproductive jitter of the reproductive signal is less than a predetermined value.
(3) An information recording apparatus comprising:
an energy beam generator for generating an energy beam;
a power adjusting mechanism for setting a power level of the energy beam to a first power level and a second power level which is higher than the first power level;
a holding mechanism for holding a recording medium permitted to get into a first state by the first power level and permitted to get into a second state by the second power level;
a moving mechanism for moving the energy beam and the recording medium relatively to each other;
a positioning mechanism for irradiating a predetermined place of the recording medium with the energy beam; and
a signal processing circuit for changing information to be recorded, into the power levels of the energy beam;
the power adjusting mechanism including:
a function of making a period of a third power level coexistent with a period of the second power level to thereby multi-pulsate the energy beam when a region of the second state is formed in the recording medium so that the region of the second state has a specific length, the third power level being equal to or less than the first power level;
a function of irradiating the recording medium with the energy beam of a fourth power level for a predetermined period following a last pulse of the multi-pulsated energy beam, the fourth power level being equal to or less than the first power level;
a function of setting the second power level multiplied by a magnification factor x to a new second power level;
a function of setting the first power level multiplied by a magnification factor y to a new first power level;
a function of setting the third power level multiplied by the magnification factor y to a new third power level; and
a function of setting the fourth power level multiplied by the magnification factor y to a new fourth power level; and
the information apparatus further comprises:
means for forming the first and second states on the recording medium by irradiating the recording medium with the energy beam while changing values of the magnification factors x and y variously;
a time interval measuring circuit for measuring fluctuation of a reproductive signal obtained by reproducing the first and second states; and
a controller for adjusting the values of the magnification factors x and y so that the value of the fluctuation of the reproductive signal obtained by the time interval measuring circuit is less than a predetermined value.
(4) An information recording apparatus comprising:
an energy beam generator for generating an energy beam;
a power adjusting mechanism for setting a power level of the energy beam to a first power level and a second power level which is higher than the first power level;
a holding mechanism for holding a recording medium permitted to get into a first state by the first power level and permitted to get into a second state by the second power level;
a moving mechanism for moving the energy beam and the recording medium relatively to each other;
a positioning mechanism for irradiating a predetermined place of the recording medium with the energy beam; and
a signal processing circuit for changing information to be recorded, into the power levels of the energy beam;
the power adjusting mechanism including:
a function of making a period of a third power level coexistent with a period of the second power level to thereby multi-pulsate the energy beam when a region of the second state is formed in the recording medium so that the region of the second state has a specific length, the third power level being equal to or less than the first power level;
a function of irradiating the recording medium with the energy beam of a fourth power level for a predetermined period following a last pulse of the multi-pulsated energy beam, the fourth power level being equal to or less than the first power level;
a function of setting the first power level multiplied by a magnification factor z to a new first power level;
a function of setting the second power level multiplied by the magnification factor z to a new second power level;
a function of setting the third power level multiplied by the magnification factor z to a new third power level; and
a function of setting the fourth power level multiplied by the magnification factor z to a new fourth power level; and
the information apparatus further comprises:
means for forming the first and second states on the recording medium by irradiating the recording medium with the energy beam while changing a value of the magnification factors z variously;
a time interval measuring circuit for measuring fluctuation of a reproductive signal obtained by reproducing the first and second states; and
a controller for adjusting the value of the magnification factor z so that the value of the fluctuation of the reproductive signal obtained by the time interval measuring circuit is less than a predetermined value.
To solve the aforementioned second problem, the following information recording method and apparatus may be used.
(1) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by forming the first and second states with predetermined lengths and at predetermined intervals on the recording medium by changing a power level of the energy beam among a plurality of power levels including the first and second power levels according to information to be recorded while moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam to thereby form a pulse string of the energy beam, the method comprising the steps of:
optimizing the first power level while fixing the second power level to a suitable initial value; and
optimizing the second power level while fixing the first power level to the optimized value.
(2) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information in the recording medium by forming the first and second states with predetermined lengths and at predetermined intervals on the recording medium by changing the energy level among a plurality of power levels including the first and second power levels according to information to be recorded while moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam to thereby form a pulse string of the energy beam, the method comprising:
at least one of a first timing adjusting method for adjusting a timing of a pulse of the energy beam which corresponds to a head portion of the second state to be formed on the recording medium, and a second timing adjusting method for adjusting a timing of a pulse of the energy beam which corresponds to a tail portion of the second state to be formed on the recording medium; and
at least one of a first adjusting procedure for adjusting the timings according to the first and second timing adjusting methods after optimizing the power levels by the information recording method described in (1), and a second adjusting procedure for optimizing the power levels by the information recording method described in (1) after adjusting the timings according to the first and second timing adjusting methods.
(3) An information recording apparatus comprising:
an energy beam generator for generating an energy beam;
a power adjusting mechanism for setting a power level of the energy beam to a first power level and a second power level which is higher than the first power level;
a holding mechanism for holding a recording medium permitted to get into a first state by the first power level and permitted to get into a second state by the second power level;
a moving mechanism for moving the energy beam and the recording medium relatively to each other;
a positioning mechanism for irradiating a predetermined place of the recording medium with the energy beam;
a signal processing circuit for changing information to be recorded into the power levels of the energy beam;
means of optimizing the first power level while fixing the second power level to a suitable initial value and then optimizing the second power level while fixing the first power level to the optimized value to thereby set the power levels in a recording mode.
(4) An information recording apparatus comprising:
an energy beam generator for generating an energy beam;
a power adjusting mechanism for setting a power level of the energy beam to a first power level and a second power level which is higher than the first power level;
a holding mechanism for holding a recording medium permitted to get into a first state by the first power level and permitted to get into a second state by the second power level;
a moving mechanism for moving the energy beam and the recording medium relatively to each other;
a positioning mechanism for irradiating a predetermined place of the recording medium with the energy beam;
a signal processing circuit for changing information to be recorded into the power levels of the energy beam;
at least one of first and second timing adjusting means, the first timing adjusting means adjusting a timing of a pulse of the energy beam corresponding to a head portion of the second state to be formed on the recording medium, and the second timing adjusting means adjusting a timing of a pulse of the energy beam corresponding to a tail portion of the second state to be formed on the recording medium; and
at least one of third and fourth timing adjusting means, the third timing adjusting means performing timing adjustment in the first and second timing adjusting means after optimizing the power levels by the optimization means according to claim 15, and the fourth timing adjusting means optimizing the power levels by the optimizing means according to claim 15 after performing the timing adjustment in the first and second timing adjusting means.
To solve the aforementioned third problem, the following information recording method and apparatus may be used.
(1) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam and the first and second states are formed on the recording medium with predetermined lengths and at predetermined intervals, comprising the steps of:
when a period of a recording timing generating clock in a recording mode is T, and a relative velocity of the energy beam and the recording medium is v,
forming a sequence of the second state with length avT (first mark), the first state with length ivT (first space) following the first mark, the second state with length mvT (second mark) following the first space, the first state with length jvT (second space) following the second mark and the second state with length bvT (third mark) following the second space as a first small recording pattern;
forming a sequence which starts with the first state and ends with the first state while the first and second states appear alternately by a finite number of times, as a second small recording pattern;
forming a state in which the second small recording pattern follows the first small recording pattern, as a basic recording pattern;
forming a state in which the basic recording patterns are repeated, as a recording pattern;
forming the recording pattern which comprises the basic recording patterns obtained by changing a parameter j variously while parameters a, i and m are fixed, as a first recording pattern, the parameters a, i, m and j being natural numbers;
forming the recording pattern which comprises the basic recording patterns obtained by changing the parameter i variously while a parameter b and the parameters j and m are fixed, as a second recording pattern, the parameter b being a natural number; and
using at least one of first and second edge position measuring methods, wherein:
the first edge position measuring method estimates a position of a boundary between the second mark and the first space by comparing a time interval from time corresponding to a mark edge position opposite to the first space of the first mark in a read signal of the first recording pattern to time corresponding to the position of the boundary between the second mark and the first space in the read signal with a time interval of (a+i)T; and
the second edge position measuring method estimates a position of a boundary between the second mark and the second space by comparing a time interval from time corresponding to the position of the boundary between the second mark and the second space in a read signal of the second recording pattern to time corresponding to a mark edge position opposite to the second space of the third mark in the read signal with a time interval of (b+i)T.
(2) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam and the first and second states are formed on the recording medium with predetermined lengths and at predetermined intervals, comprising the steps of:
when a period of a recording timing generating clock in a recording mode is T, and a relative velocity of the energy beam and the recording medium is v,
forming a sequence of the second state with length avT (first mark), the first state with length ivT (first space) following the first mark, the second state with length mvT (second mark) following the first space, the first state with length jvT (second space) following the second mark and the second state with length bvT (third mark) following the second space as a first small recording pattern;
forming a sequence which starts with the first state and ends with the first state while the first and second states appear alternately by a finite number of times, as a second small recording pattern;
forming a state in which the second small recording pattern follows the first small recording pattern, as a basic recording pattern;
forming a state in which the basic recording patterns are repeated, as a recording pattern;
forming the recording pattern which comprises the basic recording patterns obtained by changing a parameter j variously while parameters a, i and m are fixed, as a first recording pattern, the parameters a, i, m and j being natural numbers;
forming the recording pattern which comprises the basic recording patterns obtained by changing the parameter i variously while a parameter b and the parameters j and m are fixed, as a second recording pattern, the parameter b being a natural number;
using at least one of first and second edge position measuring methods; and
using at least one of first and second timing adjusting methods, wherein
the first edge position measuring method estimates a position of a boundary between the second mark and the first space by comparing a time interval from time corresponding to a mark edge position opposite to the first space of the first mark in a read signal of the first recording pattern to time corresponding to the position of the boundary between the second mark and the first space in the read signal with a time interval of (a+i)T;
the second edge position measuring method estimates a position of a boundary between the second mark and the second space by comparing a time interval from time corresponding to the position of the boundary between the second mark and the second space in a read signal of the second recording pattern to time corresponding to a mark edge position opposite to the second space of the third mark in the read signal with a time interval of (b+i)T;
the first timing adjusting method changes timing for making the energy beam reach the second power level in accordance with a combination of the respective lengths of the first and second states to be formed on the recording medium; and
the second timing adjusting method changes timing for shifting the energy beam from the second power level to another energy level in accordance with a combination of the respective lengths of the second and first states to be formed on the recording medium.
(3) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam and the first and second states are formed on the recording medium with predetermined lengths and at predetermined intervals, comprising the steps of:
when a period of a recording timing generating clock in a recording mode is T, and a relative velocity of the energy beam and the recording medium is v,
forming a sequence of the second state with length avT (first mark), the first state with length ivT (first space) following the first mark, the second state with length mvT (second mark) following the first space, the first state with length jvT (second space) following the second mark and the second state with length bvT (third mark) following the second space as a first small recording pattern;
forming a sequence which starts with the first state and ends with the first state while the first and second states appear alternately by a finite number of times, as a second small recording pattern;
forming a state in which the second small recording pattern follows the first small recording pattern, as a basic recording pattern;
forming a state in which the basic recording patterns are repeated, as a recording pattern;
forming the recording pattern which comprises the basic recording patterns obtained by changing a parameter j variously while parameters a, i and m are fixed, as a first recording pattern, the parameters a, i, m and j being natural numbers;
forming the recording pattern which comprises the basic recording patterns obtained by changing the parameter i variously while a parameter b and the parameters j and m are fixed, as a second recording pattern, the parameter b being a natural number;
using at least one of first and second edge position measuring methods;
using at least one of first and second timing adjusting methods; and
using at least one of first and second timing correcting methods, wherein
the first edge position measuring method estimates a position of a boundary between the second mark and the first space by comparing a time interval from time corresponding to a mark edge position opposite to the first space of the first mark in a read signal of the first recording pattern to time corresponding to the position of the boundary between the second mark and the first space in the read signal with a time interval of (a+i)T;
the second edge position measuring method estimates a position of a boundary between the second mark and the second space by comparing a time interval from time corresponding to the position of the boundary between the second mark and the second space in a read signal of the second recording pattern to time corresponding to a mark edge position opposite to the second space of the third mark in the read signal with a time interval of (b+i)T;
the first timing adjusting method changes timing for making the energy beam reach the second power level in accordance with a combination of the respective lengths of the first and second states to be formed on the recording medium;
the second timing adjusting method changes timing for shifting the energy beam from the second power level to another energy level in accordance with a combination of the respective lengths of the second and first states to be formed on the recording medium;
the first timing correcting method adjusts the timing in the first timing adjusting method based on a result of the first edge position measuring method; and
the second timing correcting method adjusts the timing in the second timing adjusting method based on a result of the second edge position measuring method.
(4) An information recording method using a recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, for recording information on the recording medium by moving the energy beam and the recording medium relatively to each other so that the recording medium is irradiated with the energy beam and the first and second states are formed on the recording medium with predetermined lengths and at predetermined intervals, comprising the steps of:
when a period of a recording timing generating clock in a recording mode is T, and a relative velocity of the energy beam and the recording medium is v,
forming a sequence of the second state with length avT (first mark), the first state with length ivT (first space) following the first mark, the second state with length mvT (second mark) following the first space, the first state with length jvT (second space) following the second mark and the second state with length bvT (third mark) following the second space as a first small recording pattern;
forming a sequence which starts with the first state and ends with the first state while the first and second states appear alternately by a finite number of times, as a second small recording pattern;
forming a state in which the second small recording pattern follows the first small recording pattern, as a basic recording pattern;
forming a state in which the basic recording patterns are repeated, as a recording pattern;
forming the recording pattern which comprises the basic recording patterns obtained by changing a parameter j variously while parameters a, i and m are fixed, as a first recording pattern, the parameters a, i, m and j being natural numbers;
forming the recording pattern which comprises the basic recording patterns obtained by changing the parameter i variously while a parameter b and the parameters j and m are fixed, as a second recording pattern, the parameter b being a natural number;
using at least one of first and second edge position measuring methods;
using at least one of first and second timing adjusting methods; and
using at least one of first and second timing correcting methods, wherein
the first edge position measuring method estimates a position of a boundary between the second mark and the first space by comparing a time interval from time corresponding to a mark edge position opposite to the first space of the first mark in a read signal of the first recording pattern to time corresponding to the position of the boundary between the second mark and the first space in the read signal with a time interval of (a+i)T;
the second edge position measuring method estimates a position of a boundary between the second mark and the second space by comparing a time interval from time corresponding to the position of the boundary between the second mark and the second space in a read signal of the second recording pattern to time corresponding to a mark edge position opposite to the second space of the third mark in the read signal with a time interval of (b+i)T;
the first timing adjusting method changes timing for making the energy beam reach the second power level in accordance with a combination of the respective lengths of the first and second states to be formed on the recording medium;
the second timing adjusting method changes timing for shifting the energy beam from the second power level to another energy level in accordance with a combination of the respective lengths of the second and first states to be formed on the recording medium;
the first timing correcting method operates so that
in a case where the first edge position measuring method concludes that the time interval from the time corresponding to the mark edge position opposite to the first space of the first mark in the read signal of the first recording pattern to the time corresponding to the position of the boundary between the second mark and the first space in the read signal is loner than the time interval of (a+i)T, timing of arrival at the second power level for forming the second state with length mT is quickened only when the second state with length mT is to be formed so as to follow the first state with length iT by the first timing adjusting method; and
in a case where the first edge position measuring method concludes that the time interval from the time corresponding to the mark edge position opposite to the first space of the first mark in the read signal of the first recording pattern to the time corresponding to the position of the boundary between the second mark and the first space in the read signal is shorter than the time interval of (a+i)T, the timing of arrival at the second power level for forming the second state with length mT is delayed only when the second state with length mT is to be formed so as to follow the first state with length iT by the first timing adjusting method, and
the second timing correcting method operates so that
in a case where the second edge position measuring method concludes that the time interval from the time corresponding to the position of the boundary between the second mark and the second space in the read signal of the second recording pattern to the time corresponding to the mark edge position opposite to the second space of the third mark in the read signal is loner than the time interval of (b+j)T, timing of shifting from the second power level to another energy level for forming the second state with length mT is delayed only when the first state with length jT is to be formed so as to follow the second state with length mT by the second timing adjusting method; and
in a case where the second edge position measuring method concludes that the time interval from the time corresponding to the position of the boundary between the second mark and the second space in the read signal of the second recording pattern to the time corresponding to the mark edge position opposite to the second space of the third mark in the read signal is shorter than the time interval of (b+j)T, the timing of shifting from the second power level to another energy level for forming the second state with length mT is quickened only when the first state with length jT is to be formed so as to follow the second state with length mT by the second timing adjusting method.
(5) A recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, wherein
at least one of information of timing for making the energy beam to reach the second power level and information of timing for shifting the power level from the second power level into another energy level both of which are determined using the information recording method described in (3) is recorded as not-rewritable information on the information recording medium.
(6) A recording medium permitted to get into a first state by a first power level of an energy beam and permitted to get into a second state by a second power level of the energy beam higher than the first power level, wherein
at least one of information of timing for making the energy beam to reach the second power level and information of timing for shifting the power level from the second power level into another energy level both of which are determined using the information recording method described in (4) is recorded as not-rewritable information on the information recording medium.
(7) An information recording apparatus comprising:
an energy beam generator for generating an energy beam;
a power adjusting mechanism for setting a power level of the energy beam to a first power level and a second power level which is higher than the first power level;
a holding mechanism for holding a recording medium permitted to get into a first state by the first power level and permitted to get into a second state by the second power level;
a moving mechanism for moving the energy beam and the recording medium relatively to each other;
a positioning mechanism for irradiating a predetermined place of the recording medium with the energy beam; and
a signal processing circuit for changing information to be recorded, into the power levels of the energy beam, wherein
the information recording apparatus uses the information recording medium described in (5) or (6), and
the apparatus further comprises:
means for reading the not-rewritable information recorded on the information recording medium to thereby decode at least one of the information of timing for making the energy beam to reach the second power level and the information of timing for shifting the power level from the second power level into another energy level; and
means for modulating energy pulses in accordance with the decoded information of timing when the second states is formed on the recording medium.
(8) An information recording apparatus comprising:
an energy beam generator for generating an energy beam;
a power adjusting mechanism for setting a power level of the energy beam to a first power level and a second power level which is higher than the first power level;
a holding mechanism for holding a recording medium permitted to get into a first state by the first power level and permitted to get into a second state by the second power level;
a moving mechanism for moving the energy beam and the recording medium relatively to each other;
a positioning mechanism for irradiating a predetermined place of the recording medium with the energy beam; and
a signal processing circuit for changing information to be recorded, into the power levels of the energy beam; and
means for executing at least one of the first and second timing correcting methods described in (3) or at least one of the first and second timing correcting methods described in (4).